1/2*3+1/4*7+1/7*10+1/10*13+1/13*16 不知道你们能不能看懂.看不懂的再问我把.

1/2*3+1/4*7+1/7*10+1/10*13+1/13*16
=1/2*3+1/3*(1/4-1/7)+1/3*(1/7-1/10)+1/3*(1/10-1/13)+1/3*(1/13-1/16)
=1/2*3+1/3*(1/4-1/7+1/7-1/10+1/10-1/13+1/13-1/16)
=1/2*3+1/3*(1/4-1/16)
=1/2*3+1/3*(4/16-1/16)
=1/2*3+1/3*3/16
=1/2*3+1/16
=1/6+1/16
=8/48+3/48
=11/48